The present invention relates to a tool for adjusting a drum brake of an automobile or the like, and more particularly to a new and improved configuration for the working surfaces of a brake adjusting tool for increasing the effectiveness of the tool in engaging the adjusting means of the brake.
A drum brake for an automobile or other motor vehicle comprises a radially expandable shoe that engages the interior of a drum fixedly mounted on the wheel of the vehicle. After continuous use, the surface of the shoe wears down requiring adjustment to provide a firm engagement between the shoe and drum. To this end, a star wheel is provided to serve as an adjusting implement. Rotation of the star wheel results in movement of the shoe surface toward the drum. The star wheel is mounted within the drum structure of the brake and access is facilitated by an opening through which a tool may be inserted to engage and rotate the star wheel. It has been long recognized that currently available drum brake adjusting tools, commonly referred to as brake adjusting spoons, fall far short of being adequate to provide a reliable engagement between the tool and adjusting star wheel of a drum brake. Typically, the working end of the adjusting spoon is formed to the shape of a conventional screw driver. The working end of the spoon is inserted through the opening in the drum wall and the tool is pivoted about the wall at a point on the opening by manipulating the tool handle whereby a downward movement is imparted to the working end to thereby rotate the star wheel.
A common problem associated with the above-described prior art tool is slippage. It is difficult for a mechanic to engage the star wheel and manipulate the tool without the working end slipping out of engagement with the star wheel. Moreover, it is often difficult for the mechanic to discern whether or not the tool rotated the star wheel or has slipped. Thus, adjusting a drum brake is often a tedious job due to the inadequacies of the prior adjusting spoons.
It is a primary objective of the present invention to provide a brake adjusting tool which overcomes the abovedescribed problems and which is of a rugged, inexpensive construction. Generally, the novel tool disclosed herein comprises a single member tool with a unique working end geometry which coacts with the drum brake structure to insure engagement with and rotation of the adjusting star wheel. In one advantageous form of the invention, the working end includes angled surfaces. The tool contacts the wall of the drum brake in such a manner whereby the angled surfaces urge the working end into engagement with the star wheel. Manipulation of the tool tends to further drive the working end into engagement to assure rotation of the adjusting wheel.
More specifically, the handle of the tool is formed to a narrow neck portion proximate to the working end. A portion of each of the principal surfaces of the tool is disposed at an incline. The inclined portions extend outwardly to a wide portion intermediate the neck and working end and thereafter angle toward one another to a thin blade-like working end. The dimensions of the tool are arranged such that the wide portion is just within the confines of the drum brake structure when the blade-like working end is in engagement with the star wheel. Consequently, the inclined surfaces will contact the opening of the drum wall and thereby tend to urge the working end further into engagement with the star wheel by counter-acting the natural tendency of the end to slip down and out of engagement.
These and other features and advantages of the present invention will become apparent from a reading of the following detailed description of a preferred embodiment and the accompanying drawings.